<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
</head>
<body>
    <script>
       var arr =[7,1,5,3,6,4];
       var max = 0;
       for(var i = 0;i<=arr.length;i++){
        for(var k = i+1;k<=arr.length;k++){
            var value = arr[k]-arr[i]; 
            
            if(value > max){
                max=value;  
            }
        }
       }  
       console.log(max);
        

    </script>
</body>